*
* PROBIT.RPF
* RATS Version 8, User's Guide, Example 12.1
*
open data probit.dat
data(org=obs) 1 95 public1_2 public3_4 public5 private $
   years teacher loginc logproptax yesvm
*
*  Linear probability model
*
linreg yesvm
# constant public1_2 public3_4 public5 private years teacher loginc logproptax
*
ddv(dist=logit) yesvm
# constant public1_2 public3_4 public5 private years teacher loginc logproptax
ddv(dist=probit) yesvm
# constant public1_2 public3_4 public5 private years teacher loginc logproptax
*
*  Test whether "Children in School" dummies are significant.
*  Use "Wald" test first.
*
exclude(title="Wald Test of Children in School Dummies")
# public1_2 public3_4 public5 private
*
*  Likelihood ratio test. We already have the unrestricted model.
*
compute logunres = %logl
*
ddv(dist=probit) yesvm
# constant years teacher loginc logproptax
compute logres=%logl
*
*
compute lratio=2*(logunres-logres)
cdf(title="LR Test for Children in School Dummies") chisqr lratio 4